A compensation method based on recursive processing of nonlinear distortion for OFDM

OFDM (orthogonal frequency division multiplexing) signal generates a very large signal amplitude. Consequently, distortion due to nonlinearity is produced when the signal is amplified through a nonlinear amplifier, which greatly degrades BER (bit-error rate) performance. As a method of handling this problem, this paper proposes highly accurate compensation processing of nonlinear distortion by constructing a replica of the OFDM signal in the receiver. The proposed method is based on the hard decision result of demodulated received symbols containing nonlinear distortion, and the nonlinear distortion component is recursively estimated and compensated. The performance of the proposed method is evaluated by computer simulation assuming a thermal noise environment, and it is shown that the proposed method is better in both BER and the number of constructed replicas. The performance of the proposed method is also evaluated assuming a fading environment when the method is applied to land mobile communications. The problems of fading compensation when the distortion caused by nonlinear amplification is superposed are pointed out.